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Subject[PATCH] firmware_class: Move request_firmware_nowait() to workqueues
Date
Oddly enough a work_struct was already part of the firmware_work
structure but nobody was using it. Instead of creating a new
kthread for each request_firmware_nowait() just schedule the work
on the system workqueue. This should avoid some overhead in
forking new threads when they're not strictly necessary if
workqueues are available.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
---

I saw this while looking at this problem we're having.

drivers/base/firmware_class.c | 29 +++++++----------------------
1 file changed, 7 insertions(+), 22 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 6c9387d..1010c06 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -16,7 +16,7 @@
#include <linux/interrupt.h>
#include <linux/bitops.h>
#include <linux/mutex.h>
-#include <linux/kthread.h>
+#include <linux/workqueue.h>
#include <linux/highmem.h>
#include <linux/firmware.h>
#include <linux/slab.h>
@@ -629,25 +629,18 @@ struct firmware_work {
bool uevent;
};

-static int request_firmware_work_func(void *arg)
+static void request_firmware_work_func(struct work_struct *work)
{
- struct firmware_work *fw_work = arg;
+ struct firmware_work *fw_work;
const struct firmware *fw;
- int ret;
-
- if (!arg) {
- WARN_ON(1);
- return 0;
- }
+ fw_work = container_of(work, struct firmware_work, work);

- ret = _request_firmware(&fw, fw_work->name, fw_work->device,
+ _request_firmware(&fw, fw_work->name, fw_work->device,
fw_work->uevent, true);
fw_work->cont(fw, fw_work->context);

module_put(fw_work->module);
kfree(fw_work);
-
- return ret;
}

/**
@@ -673,7 +666,6 @@ request_firmware_nowait(
const char *name, struct device *device, gfp_t gfp, void *context,
void (*cont)(const struct firmware *fw, void *context))
{
- struct task_struct *task;
struct firmware_work *fw_work;

fw_work = kzalloc(sizeof (struct firmware_work), gfp);
@@ -692,15 +684,8 @@ request_firmware_nowait(
return -EFAULT;
}

- task = kthread_run(request_firmware_work_func, fw_work,
- "firmware/%s", name);
- if (IS_ERR(task)) {
- fw_work->cont(NULL, fw_work->context);
- module_put(fw_work->module);
- kfree(fw_work);
- return PTR_ERR(task);
- }
-
+ INIT_WORK(&fw_work->work, request_firmware_work_func);
+ schedule_work(&fw_work->work);
return 0;
}

--
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.


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